1. Field of the Invention:
This invention relates to a blood cleaning hollow fiber membrane, a method for cleaning blood, and an apparatus therefor. More particularly, it relates to a blood cleaning hollow fiber membrane to be used for removing from blood a protective liquid incorporated therein for permitting frozen storage of the blood, a method for cleaning blood, and an apparatus therefor.
2. Description of the Prior Art:
In recent years, the practice of componential transfusion which comprises fractionating a donor's blood so as to choose only elements necessary for a given patient and transfusing the chosen elements into the patient is taking the place of the practice of transfusing the so-called complete blood, i.e. the blood obtained from a donor in the form containing all the elements thereof. The componential transfusion have advantages that the burden on the circulatory system can be repressed and the immunological secondary reaction alleviated as compared with the complete-blood transfusion, that only necessary elements can be transfused in a large amount at a time and, therefore, even elements contained in small proportions in the complete blood can be expected to manifest their effects sufficiently, and that elements unnecessary for one patient may be effectively utilized for some other patient [Tanaka and Shimizu: Sogo Rinsho (comprehensive clinic), Vol. 35, No. 11 (1986)]. It nevertheless is still imperfect with respect to the preclusion of the two major secondary reactions, infection and sensitization, which are entrained by the operation of transfusion. Today, the infection of patients with hepatitis, AIDS, and ATLA or the sensitization particularly of infantile patients due to transfusion of affected blood has been arousing grave anxiety to the general public. The situation is urging perfection of a preventive measure effective in curbing the impact of transfusion of affected blood.
Recently, as a prospective way of solving the problem, the autoblood transfusion method which comprises transfusing into a patient the blood collected in advance from the patient himself has been attracting growing attention. The use of the patient's own blood is essentially incapable of causing such problems as infection with virus and sensitization mentioned above. By this method, even persons of very rare blood types can be assured that they have their blood ready for transfusion in case of an accident.
In accordance with this autoblood transfusion method, the blood taken from a person himself is fractionated into component elements and, as such, put to frozen storage. Even by the latest technical standard, the blood in its liquid state can be safely preserved for 42 days at most. The frozen storage enables such fractionated blood elements to be safely preserved semipermanently and permits establishment of a system of safe transfusion.
When the fractionated blood elements are put in their unmodified form to frozen storage, such elements as erythrocytes, leukocytes, and platelets are destined to be destroyed. For these component elements to be safely preserved in the frozen storage, they require incorporation of protective liquids therein. These protective liquids are variable with research organs engaging in the development thereof and of course with particular component elements to be protected. Most of them use glycerol and dimethyl sulfoxide as main components. When they are to be returned to the owner's body, they must be defrosted, diluted, and then cleaned to be freed of the protective liquids.
For the dilution and washing, a few methods have been already put to use such as, for example, a method which, in the case of a red blood corpuscle concentrate slowly frozen as mixed with Hagging's solution (containing 79% of glycerol, 8%, of dextrose, 1% of fructose, and 0.3% of EDTA-disodium salt), for example, effects the dilution and washing by giving to the frozen concentrate mixture a first washing with 50% dextrose solution + 5% fructose solution, then a second washing with 5% fructose solution, further a third washing again with 5% fructose solution, a fourth washing with a physiological saline solution, and thereafter resuspending the washed concentrate in the phyisological saline solution [Boston Massachusetts General Hospital (Hagging) and National Fukuoka Central Hospital (Samida)] and a method which, in the case of a red blood corpuscle concentrate rapidly frozen as mixed with a Rowe solution (containing 28% of glycerol, 3% of mannitol, and 0.65% of sodium chloride), for example, effects the dilution and washing by subjecting this concentrate in its unmodified form to a first centrifugal sedimentation and discarding the supernatant, subjecting the residue of the first sedimentation to a second centrifugal sedimentation as mixed with 15% of mannitol and 0.45% of NaCl solution and discarding the resultant supernatant, subjecting the residue to a third and a fourth centrifugal sedimentation each as mixed with 0.9% NaCl solution and discarding the resultant supernatant, and finally resuspending the residue in a physiological saline solution [New York Blood Center (Rowe)].
Thus, the methods heretofore employed invariably effect the dilution and washing batchwise and necessitate either centrifugal sedimentation or centrifugal separation and involve a very complicated procedure. Moreover, they recover the component elements of blood with the efficiency hardly deserving any esteem.
An object of this invention, therefore, is to provide a blood cleaning hollow fiber membrane capable of facilitating the cleaning operation performed on frozen blood, a method for cleaning the blood, and an apparatus therefor.
Another object of this invention is to provide a blood cleaning hollow fiber membrane permitting germfree and continuous cleaning operation, a method for cleaning the blood, and an apparatus therefor.
A further object of this invention is to provide a blood cleaning hollow fiber membrane enabling component elements of blood to be recovered with high efficiency, a method for washing the blood, and an apparatus therefor.